1. Field of the Invention
The present invention is concerned with a computer aided design and manufacturing system.
2. Description of the Related Art
Conventional computer aided design and/or manufacturing systems, abbreviated hereafter to CAD/CAM, include generally a central calculating unit, a screen for making it possible to visually display the objects created and a device for entering data, such as a keyboard and/or a pointer device such as a mouse. These systems are equally provided with a user interface including programs which make it possible for the user to create or modify representations of objects by displaying them visually on the screen in two or three dimensions, so that they may be subjected to a subsequent treatment, such as for example printing on a sheet of paper or controlling a machine tool. When using such systems, the user is confronted with the problem of the initial training requiring that he memorizes a high number of commands and/or of operations for representing an object. In addition, after his training is completed, the user must often, when creating or modifying an object, carry out in a repetitive manner a series of commands or operations which are always identical for a given task, which results in increasing the time needed for the work. When a CAD/CAM system is used by a group of people, then there is the problem of standardizing the objects (drawings, plans, machining path, etc) within the company: actually, the flexibility offered by these CAD/CAM systems is such, that each user adopts a certain number of conventions or rules (options of construction in different planes, thickness of lines, type of hatching, character type), so that it becomes difficult for a person who has not executed the drawing, to modify it.
User interfaces with multiple windows make it possible to solve in part these problems. The use of a mouse, which makes it possible to move a pointer on the screen to select for example a command in a pull-down menu, diminishes the number of commands to memorize and enables a fast selection. However, for many commands, a high number of parameters must be introduced, which implies a succession of operations of the mouse in a cascade of menus appearing on the screen. Certain interfaces also use menus with icons representing diagrammatically the commands or the objects, and this improves the ergonomic aspects, but does not obviate either the need to define numerous parameters for certain operations.
The European patent EP 0 241 071 B1 teaches a CAD/CAM system using a method making it possible to create and process two-dimensional or three-dimensional models of objects and to display these models visually on a screen. A tree-structured diagram, associating a word to each hierarchical element of the object appears on the screen at the same time as the image of the model and the selection of a word in the structure diagram makes it possible to carry out an operation on the corresponding element, as well as on all the elements hierarchically inferior, thus eliminating the need to carry out this operation on each element of an inferior level. However, this system does not make it possible to decrease the number of commands or of operations to be carried out when entering the characteristic parameters of a command for creating a new model.
The purpose of the present invention is to reduce the number of operations or of commands to be carried out with a CAD/CAM system when creating a new object or when modifying an existing object. The present invention is equally aimed at improving the standardization of the results obtained with these systems, within a company.